A typical circulator is a passive radio-frequency (RF) or optical device with three or four ports where RF power entering one port is routed to the next port in a given rotation direction. A port is a location where an external waveguide or transmission line (e.g., a microstrip line or a coaxial cable) connects to the circulator device. A monolithic ferrite substrate can be used in a circulator with narrow bandwidth capacity. To achieve broadband capabilities, a composite substrate is typically used that includes ferrite materials with different magnetic properties.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.